“We are particularly concerned that one year into her detention, there remains a lack of transparency about the reasons for Ms Cheng’s detention,” Payne said in a statement.

Cheng was a business news anchor on Chinese state media’s English-language channel CGTN, where she had worked for almost a decade.

Australia expected basic standards of justice and humane treatment that met international norms, Payne said.

China’s foreign ministry said in February that all of Cheng’s rights were being “fully guaranteed”.

“We urge the Chinese government to drop the charges against our colleague, and to show compassion by allowing her to return to Australia to be with her family,” Strom said in a statement.

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Australian journalist Cheng Lei formally arrested in China for ‘illegally supplying state secrets’

Australian journalist Cheng Lei formally arrested in China for ‘illegally supplying state secrets’

On Friday, friends and former colleagues of Cheng voiced “grave concerns for her health, safety and care during her ongoing detention” in an open letter.

“We are confident she has done nothing wrong,” said the group, which includes several prominent Australian journalists and former CGTN staff.

“We are concerned about the well-being of her beloved children … They have been separated from her for well over a year now and she’s had no contact with them since her arrest,” the letter read. “We are calling for her immediate release and her return home to Australia to be reunited with her children.”

Cheng was born in China but moved with her parents to Australia as a child, and attended university in Queensland.

Several of her former colleagues at the Chinese state television network, who have since left, told Australian media outlets this week they were shocked by her detention.

Additional reporting by Agence France-Presse